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Thread: ESE's works engine tuner

  1. #37156
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    8th February 2007 - 20:42
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    Husa , the later model TZ engines would do the factory recommended 1500Km on a crank - and plenty were taken to 2000.
    Pistons happy at 500Km , and fit a new ring as soon as blowby was seen.
    Thing is at 500Km a piston would simply be worn , with double the original clearance - not ready to self destruct by falling into the port after 2 practice sessions.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  2. #37157
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    18th March 2004 - 17:38
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    Thank you Wobbly!

    Quote Originally Posted by wobbly View Post
    Diesel - here is what you want in a nutshell.
    The transfers dont need any chamfer at all as the ring does not bulge outward into the relatively small chordal widths.
    All they need is the edge at the bore broken with a cotton mop.
    A proper " chamfer " at a transfer timing edge creates severe flow eddies off the corner , causing the transfer stream to loose coherency and thus directional control.

    The big radius on the Aprilia Exhaust timing edge was instituted by Jan in response to his boss producing a new exhaust design that lost alot of top end.
    Increasing the Blowdown efficiency by dramatically increasing the just opening ports Cd value , proved to eventually give more power everywhere.
    Many years later I discovered that if you do an STA analysis on the ports , it would appear that the transfers were some 10% ahead of the Blowdown capability - just from the raw chordal data.
    But the clever implementing of an increase in Cd of the Exhaust port ( that the sim code cannot recognize unless its written in as an option ) would in reality , bring the two most important sets of port data back into alignment.
    Great stuff! So with what you were saying about the Aprilia exhaust port history do I take it the exhaust edge radius only works to a power advantage with 10% undersized ports? Or does it work to a power advantage with properly sized exhaust ports?
    Compare Pornography now to 50 years ago.
    Then extrapolate 50 years into the future.
    . . . That shit's Nasty.

  3. #37158
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    8th February 2007 - 20:42
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    At the outer limits of power capability the Transfers and Exhaust Blowdown are fighting over the same real estate.
    When I mentioned to Jan about the disparity between the STA numbers , his first reaction was that he should have tried lowering the Transfers.
    He had said previously that they were never changed in timing , only area/direction.
    Thus as always hindsight is all seeing, as his development concentrated on getting more Blowdown , firstly by enlarging the Aux , then increasing the main port Cd with a radius.

    I have no clue if dropping the Transfers and keeping the original Exhaust port geometry would have worked , but if Aprilia R&D had an accurate sim package with inbuilt STA analysis , the disparity would have been obvious
    immediately - maybe giving the insight needed into a previously unimagined development route.
    Sadly the great leader told me in person that sims were an unnecessary waste of time , same thing I thought about him as it turned out.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  4. #37159
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    18th March 2012 - 08:35
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    Next weekend is raceweekend, so we just wanted a little shakedown to see if everything worked.
    No adjustments made for traction at all.

    We reached 142km/h in roughly 100-110m (87mph in 330-345ft)
    So im hoping for personal best upcoming weekend


  5. #37160
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    18th March 2004 - 17:38
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    Radius Size?

    Quote Originally Posted by wobbly View Post
    At the outer limits of power capability the Transfers and Exhaust Blowdown are fighting over the same real estate.
    When I mentioned to Jan about the disparity between the STA numbers , his first reaction was that he should have tried lowering the Transfers.
    He had said previously that they were never changed in timing , only area/direction.
    Thus as always hindsight is all seeing, as his development concentrated on getting more Blowdown , firstly by enlarging the Aux , then increasing the main port Cd with a radius.

    I have no clue if dropping the Transfers and keeping the original Exhaust port geometry would have worked , but if Aprilia R&D had an accurate sim package with inbuilt STA analysis , the disparity would have been obvious
    immediately - maybe giving the insight needed into a previously unimagined development route.
    Sadly the great leader told me in person that sims were an unnecessary waste of time , same thing I thought about him as it turned out.
    Is there a rough rule for the radius diameter vs exhaust port size? Or is it a matter of taking what was done to late model Aprilia cylinders and trying it out?
    I must say things like this made the self important people who said two stroke development had reached a dead end in between the years 2000 and 2010 look like the pompous idiots they really are.
    Compare Pornography now to 50 years ago.
    Then extrapolate 50 years into the future.
    . . . That shit's Nasty.

  6. #37161
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    20th April 2011 - 08:45
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    Quote Originally Posted by diesel pig View Post
    Is there a rough rule for the radius diameter vs exhaust port size? Or is it a matter of taking what was done to late model Aprilia cylinders and trying it out?
    Here you go Diesel.
    Click image for larger version. 

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  7. #37162
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    Thank you Frits!

    Quote Originally Posted by Frits Overmars View Post
    Here you go Diesel.
    Click image for larger version. 

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    Perfect! With it in percentages it can be converted into any size. Top Man.
    Compare Pornography now to 50 years ago.
    Then extrapolate 50 years into the future.
    . . . That shit's Nasty.

  8. #37163
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    12th October 2016 - 01:24
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    Frits, I'm curious about the process of arriving at the radius of 5% of stroke.

    Backing into the result...
    In 2D CFD analysis the vena contracta is almost nonexistent when the port first opens and grows as the pressure ratio falls. A larger radius will have a more gradual port opening as the effective downward angle of the port swings from 75 to whatever the port roof is ~20-25 A Radius of 5% makes this transition in ~3.5 and seems optimized for a pressure ratio of ~1.6 or about the end of the blow down phase. This makes the radius large enough to prevent separation through all of blowdown, but would need the timing edge adjusted depending on where the radius is relative to the original timing edge.

    If the timing edge were held constant with the radius effectively built up on the roof of the port, then the early blowdown phase will flow less because the radius blocks the path.
    If the port roof were held constant with the radius being further cut upward then the timing is truly changed with blowdown starting earlier.
    Using the wire bent at 45 to measure the timing edge seems to split the difference.

    Click image for larger version. 

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    Patrick Owens
    www.OopsClunkThud.com

  9. #37164
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    8th February 2007 - 20:42
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    I would be interested to see the CFD analysis where , as in the Aprilia the radius I believe started at 202* duration , but the actual port roof angled at 25* was 196* - and measured
    with the 0.7mm gauge the effective timing was at 198*.
    Would be interesting to know what the original conventional roof timing was.
    But what happens a bit further down the duct is just as important in my recent testing. For best power the 25* down angle turns into a convex radius , and the port floor is horizontal to the point
    where the side ports enter the main duct, and then turns into a downward angled ski jump.
    This minimizes the main duct area , exactly where the side ports are increasing the effective total.
    When combined with the 75% exit area , this configuration gives a huge increase in power everywhere, simply changing the duct geometry.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  10. #37165
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    Honestly, i dont think its needed to follow the blueprint 100% on that radiused top of exhaust.
    As i know that when putting velocitystacks on a inlet (fourstroke), is like the first 90% of gains is just a chamfer on the straight pipe.

  11. #37166
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    Quote Originally Posted by OopsClunkThud View Post
    Frits, I'm curious about the process of arriving at the radius of 5% of stroke.
    Patrick, that 5% value was established empirically and given the number of possible combinations (the size of the radius and the offset of its center relative to the bore) we cannot exclude that the optimum might be a percent more or less.
    I've always been playing with radii. It started when, at age 15, I radiused the piston top edge of my moped. Of course I didn't know what I was doing, but it worked.
    I started fiddling with the exhaust port timing edge after reading about it in a book that I cherish. It is older than I am and it was written by professor Alfred Jante. He came up with 5%, also established empirically .

    Quote Originally Posted by wobbly View Post
    I would be interested to see the CFD analysis where , as in the Aprilia the radius I believe started at 202* duration , but the actual port roof angled at 25* was 196* - and measured with the 0.7mm gauge the effective timing was at 198*. Would be interesting to know what the original conventional roof timing was.
    Both the 196 timing before radiusing the top edge and the 202 timing after radiusing were established with 'first light' visible at the ports top edge; no 45-bent gage involved. I came up with the bent gage later, when trying to establish the effects of combined radii at both the port top edge and the piston top edge.

    Quote Originally Posted by wobbly View Post
    what happens a bit further down the duct is just as important in my recent testing. For best power the 25* down angle turns into a convex radius , and the port floor is horizontal to the point where the side ports enter the main duct, and then turns into a downward angled ski jump. This minimizes the main duct area , exactly where the side ports are increasing the effective total. When combined with the 75% exit area , this configuration gives a huge increase in power everywhere, simply changing the duct geometry.
    Wob, I am well aware of the excellent results that can be achieved with your exhaust duct geometry. However I think that minimizing the main duct area, exactly where the side ports are increasing the effective total, is not a goal in itself but a consequence of the fact that the cross flow area upstream of this minimum area is larger than it ought to be.
    Raising the exhaust floor to about 10 crankshaft degrees below Transfer Opening would reduce the initial port area while leaving sufficient blowdown angle.area for even the most enthusiastic overrev. It would also reduce the risk of transfer short-circuiting, it would influence the horizontal course of the port floor, reducing or eliminating the ski hump, and it would raise the exit area value to over 75%.

  12. #37167
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    Quote Originally Posted by SwePatrick View Post
    Honestly, i dont think its needed to follow the blueprint 100% on that radiused top of exhaust.
    As i know that when putting velocitystacks on a inlet (fourstroke), is like the first 90% of gains is just a chamfer on the straight pipe.
    But if you were going for that 100% an ellipse with a semi-minor axis of 5% and a semi-major axis of ~10% would be even better than a radius.
    Patrick Owens
    www.OopsClunkThud.com

  13. #37168
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    Frits I have signed an NDA with another KZ engine manufacturer who is desperate ( and has all the resource ) to try all of the things we have been discussing.
    Initially all my work will be remote , in CAD ,up until the end of August where I am committed here to winning our KZ National Title again.
    After that a flying visit to you and Marc is pretty much a done deal.
    First order of the day is to do the cylinder/pipe analysis in EngMod , then carry on where Jan left off with the floor at 3mm ABDC.
    Maybe I can retire when its at 9mm above.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  14. #37169
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    Quote Originally Posted by wobbly View Post
    Frits I have signed an NDA with another KZ engine manufacturer who is desperate ( and has all the resource ) to try all of the things we have been discussing.
    Initially all my work will be remote , in CAD ,up until the end of August where I am committed here to winning our KZ National Title again.
    After that a flying visit to you and Marc is pretty much a done deal.
    First order of the day is to do the cylinder/pipe analysis in EngMod , then carry on where Jan left off with the floor at 3mm ABDC.
    Maybe I can retire when its at 9mm above.
    I'm looking forward to it Wob

  15. #37170
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    Quote Originally Posted by husaberg View Post
    Confused i thought 1000km or so for the pistons half that for the rings with the cranks about 2000km that prior the big bangs. the price of power i would guess the 125 ad 250s were changing stuff at a much quicker rate.
    pistons every race cranks at 100
    Quote Originally Posted by wobbly View Post
    Frits I have signed an NDA with another KZ engine manufacturer who is desperate ( and has all the resource ) to try all of the things we have been discussing.
    Initially all my work will be remote , in CAD ,up until the end of August where I am committed here to winning our KZ National Title again.
    After that a flying visit to you and Marc is pretty much a done deal.
    First order of the day is to do the cylinder/pipe analysis in EngMod , then carry on where Jan left off with the floor at 3mm ABDC.
    Maybe I can retire when its at 9mm above.
    That is great news !
    Will this assignment also give you the opportunity to experiment with longer conrods (like aprilia had in the RSA, in sharp contrast to the short honda conrods ) or is it limited to the current 110 or 115mm that is used in KZ ?

    I am gonna be cheering for you, winning the KZ Kiwi national title !

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